The degree to which gamma ray bursts are collimated is now the dominant uncertainty in their energy requirements and event rates. In this review I begin with the reasons for studying GRB collimation, then discuss existing tests for collimation and their applications to date, and finally outline some possible future tests. The most important conclusions are that (1) mean collimation angles much ...

The sweep system for the heavy ion beam probe on the Madison Symmetric Torus ~MST! is described. The two components of the system are the primary sweep optics and secondary collimation plates. Key issues in the sweep system design are the small entrance and exit ports available on MST, the significant toroidal beam motion induced by the strong poloidal magnetic field, and the excessive current ...

A design study has been performed for a lightweight, cylindrical array antenna for a hostile-mortar-locating radar system. A mathematical model of the array was developed which permitted tradeoff studies to be made of various array parameters. Data computed using the model compared very well with experimental and other theoretical data. Critical components of the array were built and tested and...

All-optical approaches to particle acceleration are currently attracting a significant research effort internationally. Although characterized by exceptional transverse and longitudinal emittance, laser-driven ion beams currently have limitations in terms of peak ion energy, bandwidth of the energy spectrum and beam divergence. Here we introduce the concept of a versatile, miniature linear acce...

In this work, we investigate the propagation of designer surface plasmons in planar perfect electric conductor structures that are subject to a parabolic graded-index distribution. A three-dimensional, fully vectorial finite-difference time-domain method was used to engineer a structure with a parabolic effective group index by modulating the dielectric constant of the structure's square holes....

Hydroxyapatite bioceramic was used for the manufacture of an orbital floor prosthesis from spiral CT data acquired transaxially at 1-mm beam collimation, pitch of 1, and 0.2-mm reconstruction intervals. CT data were converted to vector file format for subsequent prosthesis manufacture on a stereo-lithography machine. The orbital floor prosthesis was engrafted onto an acrylic model of the orbit ...

Traditionally, most MDCT systems employ a post collimation anti-scatter grid (ASG) in the angular (X) direction to compensate for the scatter radiation. However, with increasing Z-axis coverage offered by advanced state-of-the-art multi-slice CT (MSCT) scanners, the scatter level increases significantly and there is an opportunity to use software algorithms to further decrease the impact of sca...

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A simple direct acceleration model is proposed, taking into account the stochastic phase disturbance of the coherent driving laser fields. A relativistic single particle simulation shows that plasma electrons are efficiently accelerated far above the ponderomotive energy. The energy and momentum distributions of the accelerated electrons are derived to examine the effects of the self-generated ...

A Penning-type negative hydrogen (H) ion source has been used reliably on the ISIS pulsed spallation neutron and muon facility at the Rutherford Appleton Laboratory (RAL) in the UK for almost 30 years. However a detailed study of the ion source plasma and extraction has never been undertaken. If these properties were known, the beam emittance and losses due to collimation could be reduced, and ...